It's turning out to be an important time for extraordinary watches. First, Christie's sold the most expensive Rolex ever, and now Forbes reports that Sotheby's will be auctioning off five rare Patek Philippe titanium watches at its June 10 Important Watches auction in New York.

The superstar of the bunch is the Ref 5001 Sky Moon Tourbillon, the only watch of its kind made from titanium, and one so rare that no one but its unnamed current owner was aware it even existed before it was brought to auction. The Ref 5001 Sky Moon Tourbillon could sell for as much as $1.5 million, with the latter price topping the recently sold cloisonné enamel dial Rolex Oyster Perpetual, which is now officially the most expensive Rolex ever sold. Ballers get those wallets ready.